1. Field of the Invention
The invention relates to the catalytic polymerization of ethylene, alone, or with other .alpha.-olefin monomers.
2. Description of the Prior Art
U.S. Pat. No. 3,709,853 discloses the use of an inorganic oxide supported bis-cyclopentadienyl chromium [II] compound as a catalyst for the polymerization of ethylene alone, or with other .alpha.-olefins.
The polymerization activity of these catalysts, however, tends to drop off rapidly after the catalysts have been in use for one to two hours. The ethylene polymers made with this catalyst, moreover, tend to be of very high molecular weight, i.e., having relatively very low melt index values, unless the catalyst is used with hydrogen. The catalyst's response to hydrogen, however, as a melt index regulator, is very high, making it difficult to readily control the melt index properties of the polymer under large scale commercial polymerization procedures.